The present invention is directed to an emergency disconnect tool for use in a well drilling conduit for use in the event the drilling assembly becomes stuck.
While drilling wells, it is possible that the drilling assembly may become struck downhole. Simply pulling the drill string from the surface may be insufficient to free the drilling assembly, particularly in drilling operations and more particularly in horizontal drilling operations involving coiled tubing. Simply pulling the drill string from the surface can cause unpredictable tensile failure of the drill string due to the uncontrolled location or force required to part the tubing, resulting in expensive loss of equipment and abandonment of the well.
To overcome the problem of removing stuck drilling assemblies, various shear devices, such as disclosed in U.S. Pat. No. 5,070,941, have been proposed or used to internally shear the drill string.
In particular, typical coil tubing drilling applications use a hydraulic control line and an electric cable inside the coil tubing to actuate a lower drilling assembly such as disclosed in copending patent application Ser. No. 07/963,864, filed Oct. 20, 1992.
The present invention is directed to an improved disconnect tool which may use either the hydraulic control line and/or the electrical cable to disconnect the tool and which separate the control line and the electrical cable at a desired location.